@article{gomez-maldonado_peresin_verdi_velarde_saloni_2020, title={Thermal, Structural, and Mechanical Effects of Nanofibrillated Cellulose in Polylactic Acid Filaments for Additive Manufacturing}, volume={15}, ISSN={["1930-2126"]}, DOI={10.15376/biores.15.4.7954-7964}, abstractNote={As the additive manufacturing process gains worldwide importance, the need for bio-based materials, especially for in-home polymeric use, also increases. This work aims to develop a composite of polylactic acid (PLA) and nanofibrillated cellulose (NFC) as a sustainable approach to reinforce the currently commercially available PLA. The studied materials were composites with 5 and 10% NFC that were blended and extruded. Mechanical, structural, and thermal characterization was made before its use for 3D printing. It was found that the inclusion of 10% NFC increased the modulus of elasticity in the filaments from 2.92 to 3.36 GPa. However, a small decrease in tensile strength was observed from 55.7 to 50.8 MPa, which was possibly due to the formation of NFC aggregates in the matrix. This work shows the potential of using PLA mixed with NFC for additive manufacturing.}, number={4}, journal={BIORESOURCES}, author={Gomez-Maldonado, Diego and Peresin, Maria Soledad and Verdi, Christina and Velarde, Guillermo and Saloni, Daniel}, year={2020}, month={Nov}, pages={7954–7964} }
 @article{peresin_vesterinen_habibi_johansson_pawlak_nevzorov_rojas_2014, title={Crosslinked PVA nanofibers reinforced with cellulose nanocrystals: Water interactions and thermomechanical properties}, volume={131}, ISSN={0021-8995}, url={http://dx.doi.org/10.1002/APP.40334}, DOI={10.1002/app.40334}, abstractNote={ABSTRACTAcid‐catalyzed vapor phase esterification with maleic anhydride was used to improve the integrity and thermo‐mechanical properties of fiber webs based on poly(vinyl alcohol), PVA. The fibers were produced by electrospinning PVA from aqueous dispersions containing cellulose nanocrystals (CNCs). The effect of esterification and CNC loading on the structure and solvent resistance of the electrospun fibers was investigated. Chemical characterization of the fibers (FTIR, NMR) indicated the formation of ester bonds between hydroxyl groups belonging to neighboring molecules. Thermomechanical properties after chemical modification were analyzed using thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. An 80% improvement in the ultimate strength was achieved for CNC‐loaded, crosslinked PVA fiber webs measured at 90% air relative humidity. Besides the ultra‐high surface area, the composite PVA fiber webs were water resistant and presented excellent mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40334.}, number={11}, journal={Journal of Applied Polymer Science}, publisher={Wiley}, author={Peresin, Maria Soledad and Vesterinen, Arja-Helena and Habibi, Youssef and Johansson, Leena-Sisko and Pawlak, Joel J. and Nevzorov, Alexander A. and Rojas, Orlando J.}, year={2014}, month={Jan}, pages={n/a-n/a} }
 @article{peresin_habibi_vesterinen_rojas_pawlak_seppala_2010, title={Effect of Moisture on Electrospun Nanofiber Composites of Poly(vinyl alcohol) and Cellulose Nanocrystals}, volume={11}, ISSN={["1526-4602"]}, DOI={10.1021/bm1006689}, abstractNote={The effect of humidity on the morphological and thermomechanical properties of electrospun poly(vinyl alcohol) (PVA) fiber mats reinforced with cellulose nanocrystals (CNs) was investigated. Scanning electron microscopy (SEM) images revealed that the incorporation of CNs improved the morphological stability of the composite fibers even in high humidity environments. Thermal and mechanical properties of the electrospun fiber mats were studied by using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and large deformation tensile tests under controlled humidity and temperatures. The balance between the moisture-induced plasticization and the reinforcing effect of rigid CN particles was critical in determining the thermomechanical behaviors of the electrospun fiber mats. Results indicated that the stabilizing effect of the CNs in the PVA matrix might be compromised by water absorption, disrupting the hydrogen bonding within the structure. The amount of this disruption depended on the surrounding humidity and the CN loading. The reduction in tensile strength of neat PVA fiber mats as they were conditioned from low relative humidity (10% RH) to high relative humidity (70% RH) was found to be about 80%, from 1.5 to 0.4 MPa. When the structure was reinforced with CNs, the reduction in strength was limited to 40%, from 2 to 0.8 MPa over the same range in relative humidity. More importantly, the CN-loaded PVA fiber mats showed a reversible recovery in mechanical strength after cycling the relative humidity. Finally, humidity treatments of the composite PVA fiber mats induced significant enhancement of their strength as a result of the adhesion between the continuous matrix and the CNs.}, number={9}, journal={BIOMACROMOLECULES}, author={Peresin, Maria S. and Habibi, Youssef and Vesterinen, Arja-Helena and Rojas, Orlando J. and Pawlak, Joel J. and Seppala, Jukka V.}, year={2010}, month={Sep}, pages={2471–2477} }
 @article{peresin_habibi_zoppe_pawlak_rojas_2010, title={Nanofiber Composites of Polyvinyl Alcohol and Cellulose Nanocrystals: Manufacture and Characterization}, volume={11}, ISSN={["1526-4602"]}, DOI={10.1021/bm901254n}, abstractNote={Cellulose nanocrystals (CN) were used to reinforce nanofibers in composite mats produced via electrospinning of poly(vinyl alcohol) (PVA) with two different concentrations of acetyl groups. Ultrathin cross-sections of the obtained nanocomposites consisted of fibers with maximum diameters of about 290 nm for all the CN loads investigated (from 0 to 15% CN loading). The electrospinning process did not affect the structure of the PVA polymer matrix, but its degree of crystallinity increased significantly together with a slight increase in the corresponding melting temperature. These effects were explained as being the result of alignment and enhanced crystallization of PVA chains within the individual nanofibers that were subjected to high shear stresses during electrospinning. The strong interaction of the PVA matrix with the dispersed CN phase, mainly via hydrogen bonding or bond network, was reduced with the presence of acetyl groups in PVA. Most importantly, the elastic modulus of the nanocomposite mats increased significantly as a consequence of the reinforcing effect of CNs via the percolation network held by hydrogen bonds. However, this organization-driven crystallization was limited as observed by the reduction in the degree of crystallinity of the CN-loaded composite fibers. Finally, efficient stress transfer and strong interactions were demonstrated to occur between the reinforcing CN and the fully hydrolyzed PVA electrospun fibers.}, number={3}, journal={BIOMACROMOLECULES}, author={Peresin, Maria S. and Habibi, Youssef and Zoppe, Justin O. and Pawlak, Joel J. and Rojas, Orlando J.}, year={2010}, month={Mar}, pages={674–681} }
 @article{zoppe_peresin_habibi_venditti_rojas_2009, title={Reinforcing Poly(ε-caprolactone) Nanofibers with Cellulose Nanocrystals}, volume={1}, ISSN={1944-8244 1944-8252}, url={http://dx.doi.org/10.1021/am9003705}, DOI={10.1021/am9003705}, abstractNote={We studied the use of cellulose nanocrystals (CNXs) obtained after acid hydrolysis of ramie cellulose fibers to reinforce poly(epsilon-caprolactone) (PCL) nanofibers. Chemical grafting with low-molecular-weight PCL diol onto the CNXs was carried out in an attempt to improve the interfacial adhesion with the fiber matrix. Grafting was confirmed via infrared spectroscopy and thermogravimetric analyses. The polymer matrix consisted of electrospun nanofibers that were collected as nonwoven webs. The morphology as well as thermal and mechanical properties of filled and unfilled nanofibers were elucidated by scanning electron microscopy, differential scanning calorimetry, and dynamic mechanical analysis, respectively. The addition of CNXs into PCL produced minimal changes in the thermal behavior of the electrospun fibers. However, a significant improvement in the mechanical properties of the nanofibers after reinforcement with unmodified CNXs was confirmed. Fiber webs from PCL reinforced with 2.5% unmodified CNXs showed ca. 1.5-fold increase in Young's modulus and the ultimate strength compared to PCL webs. Compared to the case of grafted nanocrystals, the unmodified ones imparted better morphological homogeneity to the nanofibrillar structure. The grafted nanocrystals had a negative effect on the morphology of nonwoven webs in which individual nanofibers became annealed during the electrospinning process and, therefore, could not be compared to neat PCL nonwoven webs. A rationalization for the different effects of grafted and unmodified CNXs in reinforcing PCL nanofibers is provided.}, number={9}, journal={ACS Applied Materials & Interfaces}, publisher={American Chemical Society (ACS)}, author={Zoppe, Justin O. and Peresin, Maria S. and Habibi, Youssef and Venditti, Richard A. and Rojas, Orlando J.}, year={2009}, month={Aug}, pages={1996–2004} }